1. Field of the Invention
The present invention relates to pump assemblies. More specifically, it relates to self-powered microminiature bladder pumps which may be used as bio-compatible medical implants for controlling diseases such as glaucoma and hydrocephalus, and to effect drug delivery.
2. Description of the Prior Art
Mechanical and electro-mechanical medical implants are well known, and, depending upon the type, have met with varying success rates. One problem with these devices is the lack of a reliable, long term power source. Ideally, the power source should last for the life of the implant, as many of these implants require invasive procedures both to install and maintain. Indeed, an external power source is virtually impossible in many situations, making the use of internal, self-contained power sources highly preferable.
One use for mechanical implants is the treatment of glaucoma. Glaucoma is a common eye disease which is caused by excessive ocular pressure in the anterior chamber of the eyeball. Many devices and techniques have been devised in order to control this pressure. The devices fall generally into two types; passive devices such as a simple tubular shunt or similar device which drains aqueous humor from the anterior chamber, and active devices which have means for controllably draining ocular pressure by pumping out a small amount of aqueous humor, the systems typically using check valves or similar mechanical devices to regulate pump action. While these systems are somewhat effective, they tend to suffer from the drawback in that they are unreliable or require frequent maintenance which always involves a fairly invasive procedure. Failure to properly maintain the devices can result in long term damage to surrounding tissue especially in the case of pumps used to control glaucoma. Power sources for these implantable pumps have to be either implantable batteries that need to be replaced after a while or transcutaneously charged every once in a while or inductive energy sources which tend to be cumbersome because an inductive energy receiving armature needs to implanted alongside with them and an inductive energy source needs to be brought close to them to induce current and subsequently energize the device.
U.S. Pat. No. 5,370,607 issued to Memmen discloses a glaucoma implant device which has a tubular shunt for draining fluid from the eye.
U.S. Pat. No. 4,911,616 issued to Laumann, Jr. discloses a microminiature pump which may be used to administer medications in sensitive locations in the body such as the eye. The pump is programmable, but the patent does not disclose which aspects of the pump operation can be controlled.
U.S. Pat. No. 5,062,841 issued to Siegel discloses an insulin pump which can be used to pump insulin directly into the bloodstream in response to blood glucose levels.
U.S. Pat. No. 5,433,701 issued to Rubinstein discusses an active ocular pressure control device which, in one embodiment, includes a pump which is selectively operated in response to a control signal from a pressure sensor.
The present invention contemplates a pumping system which utilizes a flexible, pressure reactive bladder as the primary actuator. The system harvests its operational power from the random dynamic motion of its implantation environment.